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From: Peter Zijlstra <peterz@infradead.org>
To: Matt Fleming <matt@console-pimps.org>
Cc: Guenter Roeck <linux@roeck-us.net>,
	Matt Fleming <matt.fleming@intel.com>,
	linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] firmware: Do not use WARN_ON(!spin_is_locked())
Date: Wed, 13 Aug 2014 16:44:58 +0200	[thread overview]
Message-ID: <20140813144458.GS9918@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20140813141836.GQ15082@console-pimps.org>

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On Wed, Aug 13, 2014 at 03:18:36PM +0100, Matt Fleming wrote:
> On Sun, 10 Aug, at 08:54:13PM, Guenter Roeck wrote:
> > spin_is_locked() always returns false for uniprocessor configurations,
> > so do not use WARN_ON with it. WARN_ON_SMP() exists for that very
> > purpose and must be used instead.
>  
> 
> How about lockdep_assert_held()? That seems to be much more popular.

lockdep_assert_held() not only checks if the lock is taken, it also
verifies its taken by the current context, so its a stronger assertion.

And, as a bonus, it doesn't emit _any_ code on a !DEBUG build ;-)

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WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
To: Matt Fleming <matt-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org>
Cc: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>,
	Matt Fleming
	<matt.fleming-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] firmware: Do not use WARN_ON(!spin_is_locked())
Date: Wed, 13 Aug 2014 16:44:58 +0200	[thread overview]
Message-ID: <20140813144458.GS9918@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20140813141836.GQ15082-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org>

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On Wed, Aug 13, 2014 at 03:18:36PM +0100, Matt Fleming wrote:
> On Sun, 10 Aug, at 08:54:13PM, Guenter Roeck wrote:
> > spin_is_locked() always returns false for uniprocessor configurations,
> > so do not use WARN_ON with it. WARN_ON_SMP() exists for that very
> > purpose and must be used instead.
>  
> 
> How about lockdep_assert_held()? That seems to be much more popular.

lockdep_assert_held() not only checks if the lock is taken, it also
verifies its taken by the current context, so its a stronger assertion.

And, as a bonus, it doesn't emit _any_ code on a !DEBUG build ;-)

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  parent reply	other threads:[~2014-08-13 14:45 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-08-11  3:54 [PATCH] firmware: Do not use WARN_ON(!spin_is_locked()) Guenter Roeck
2014-08-11  3:54 ` Guenter Roeck
2014-08-13 14:18 ` Matt Fleming
2014-08-13 14:18   ` Matt Fleming
2014-08-13 14:37   ` Guenter Roeck
2014-08-13 14:37     ` Guenter Roeck
2014-08-13 15:02     ` Matt Fleming
2014-08-13 15:02       ` Matt Fleming
2014-08-13 23:31       ` Theodore Ts'o
2014-08-13 23:31         ` Theodore Ts'o
2014-08-13 14:44   ` Peter Zijlstra [this message]
2014-08-13 14:44     ` Peter Zijlstra

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